Due Date Calculator
Find your estimated due date and exactly how far along you are today.
Choose a date above to see your due date and how far along you are.
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How this due date calculator works
The estimate uses Naegele's rule: a full-term pregnancy is counted as 280 days (40 weeks) from the first day of your last period. If you know your conception or IVF transfer date, the calculator counts forward from there instead, 266 days from conception, adjusted for a 3-day or 5-day embryo transfer.
Last period, conception, or IVF?
Pick whichever date you know best. Last period is the most common and lets you fine-tune for your cycle length. Conception works if you tracked ovulation. IVF dates tend to be the most precise because the timing is known exactly.
Why the range matters more than the date
A due date is really the middle of a normal window. Full term is anywhere from 37 to 42 weeks, so it helps to think of it as a due month rather than a single day.
Common questions
How accurate is a due date calculator?
It gives a solid estimate, but only about 1 in 20 babies arrive on their exact due date. Most are born within two weeks either side. An early ultrasound is often the most accurate way to date a pregnancy.
Is pregnancy counted from my last period or conception?
By convention, pregnancy is dated from the first day of your last menstrual period, about two weeks before conception actually happens. That is why 40 weeks of pregnancy is roughly 38 weeks from conception.
What if my cycles are irregular or longer than 28 days?
Adjust the cycle-length slider to match your average. Longer cycles usually mean later ovulation, which moves the estimated due date slightly later.
Can my due date change?
Yes. Early ultrasound measurements can shift the date by several days, and that scan-based date is usually treated as the most accurate.
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